title: Antigen and lymphopenia-driven donor T cells are differentially diminished by post-transplantation administration of cyclophosphamide after hematopoietic cell transplantation.
abstract: Administration of cyclophosphamide after transplantation (post-transplantation cyclophosphamide, PTC) has shown promise in the clinic as a prophylactic agent against graft-versus-host disease (GVHD). An important issue with regard to recipient immune function and reconstitution after PTC is the extent to which, in addition to diminution of antihost allo-reactive donor T cells, the remainder of the nonhost allo-reactive donor T cell pool may be affected. To investigate PTC's effects on nonhost reactive donor CD8 T cells, ova-specific (OT-I) and gp100-specific Pmel-1 T cells were labeled with proliferation dyes and transplanted into syngeneic and allogeneic recipients. Notably, an intermediate dose (66 mg/kg) of PTC, which abrogated GVHD after allogeneic HSCT, did not significantly diminish these peptide-specific donor T cell populations. Analysis of the rate of proliferation after transplantation illustrated that lymphopenic-driven, donor nonhost reactive TCR Tg T cells in syngeneic recipients underwent slow division, resulting in significant sparing of these donor populations. In contrast, after exposure to specific antigens at the time of transplantation, these same T cells were significantly depleted by PTC, demonstrating the global susceptibility of rapidly dividing T cells after an encounter with cognate antigen. In total, our results, employing both syngeneic and allogeneic minor antigen-mismatched T cell replete models of transplantation, demonstrate a concentration of PTC that abrogates GVHD can preserve most cells that are dividing because of the accompanying lymphopenia after exposure. These findings have important implications with regard to immune function and reconstitution in recipients after allogeneic hematopoietic stem cell transplantation.
authors.affiliation: Departments of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Duncan
authors.initials: D
authors.lastname: Ross
authors.forename: Monica
authors.initials: M
authors.lastname: Jones
authors.forename: Krishna
authors.initials: K
authors.lastname: Komanduri
authors.forename: Robert B
authors.initials: RB
authors.lastname: Levy
mesh_terms: D000818:Animals; D003520:Cyclophosphamide / Q000008:administration & dosage*; D005260:Female; D006086:Graft vs Host Disease / Q000276:immunology* / Q000517:prevention & control; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006801:Humans; D008213:Lymphocyte Activation; D008231:Lymphopenia / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000276:immunology*; D019172:Transplantation Conditioning / Q000379:methods*; D014184:Transplantation, Homologous
chemical_list: D003520:Cyclophosphamide
keywords: Alkylating agent; Allogeneic-hematopoietic stem cell transplantation (HSCT); Graft-versus-host disease (GVHD); Lymphopenia-induced proliferation; Myeloablative conditioning; Post-transplantation cyclophosphamide